Antifriction bearing worm and gear mechanism



June 15, 1965 P. E. SCHMIDT 3,188,877

ANTIFRICTION BEARING WORM AND GEAR MECHANISM Filed June 17, 1963 2Sheets-Sheet 1 FIG.

INVENTOR. PAUL E. SCHMIDT ATTORNEY June 15, 1965 P. E. SCHMIDT 3,188,877

ANTIFRICTION BEARING WORM AND GEAR MECHANISM Filed June 17, 1963 2Sheets-Sheet 2 FIG. 3 35 39 INVENTOR.

D L E. SCHMIDT ATTORNEY being practiced and carried out in various ways.

United States Patent Another object of this invention is the provisionof a novel and reliable antifriction bearing worm and gear mechanismthat has a minimum number of parts, requires a minimum of lubrication,can be fabricated at relatively small expense, and is durable inconstruction.

A still further object of this invention is the provision of a novel andreliable antifriction ball bearing worm and gear mechanism having slackadjusting means carried by the gear for preventing jamming of the gearand Worm due to the displacement of one or more of the antifriction ballbearings.

Yet another object of this invention is the provision of a novelantifriction ball bearing worm and gear mechanism having means forassuring that the antifriction ball bearings are resiliently urged intoa fully seated and operative relationship between the worm and gear atthe point of tangency thereof for maximum power transmission and optimummechanical efiiciency of the gear assembly entirely throughout the speedranges in which the gear assembly is intended to be operated.

The invention further resides in certain novel features of construction,combinations, and arrangements of parts, and further objects andadvantages of the invention will be apparent to those skilled in the artto which it pertains from the following description of the presentpreferred embodiment thereof described with reference to theaccompanying drawings, which form a part of this specification, whereinthe same reference numerals indicate corresponding parts throughoutseveral views, and in which;

FIG. 1 is a side elevational view, with parts broken away and insection, of an antifriction worm and gear mechanism embodying theinvention;

FIG. 2 is an enlarged fragmentary side elevational view of a portion ofthe antifriction worm and gear of FIG. 1 in fully engaged and powertransmitting position at the point of tangency thereof; and

FIG. 3 is an enlarged sctional view along line 3-3 in FIG. 1.

It is to be understood that the invention is not limited to the detailsof construction and the arrangements of parts shown in the drawings andhereafter described in detail, but is capable of being otherwiseembodied and of It is to be further understood that the terminologyemployed herein is for the purpose of description and there is nointention to herein limit the invention beyond the requirements of theprior art.

' Referring to FIG. 1, a power transmitting mechanism embodying theinvention is indicated generally by the reference numeral 19. Themechanism comprises a power input shaft 11 having an antifriction worm12 connected thereto. A gear 13 is preferably driven by the 3,188,877Patented June 15, 1965 Ice worm 12 through an interconnecting powertransmitting antifriction means comprising recirculating antifrictionbearing balls 14. The worm 12 is journaled in a housing 15 by means oftwo coaxial double row ball bearing assemblies 16 and 17. The gear 13 iskeyed to an output shaft 18 journaled in the housing 15. The housing 15has a generally J-shaped cross section as seen in FIG. 3. The gear 13has a plurality of helical and substantially semicylindrical ballreceiving recesses 20 preferably wide enough to permit at least twopower transmitting balls 14 to be seated therein and drivingly engagethe gear 13. It is understood that the recesses 20 may be wide enough toaccommodate only one ball 14, but this would shorten the useful wearlife of the gear 13.

Slack adjusting, vibration damping, and noise reducing tubular members21, of flexible and resilient material, are each seated and fixed into asubstantially semicylindrical recess 22. One recess 22 is formed in andcoextensive with the bottom of each ball receiving recess 20. Therecesses 20 and 22 have centers that are coincidental with radii of thegear 13, FIG. 3. The recesses 20 have central axes that define acylinder having a center coincidental with the common center ofrevolution of the gear 13 and the output shaft 18. The tubular members21 preferably extend the length of the recesses 20 and 22 and lie in acircle that is concentric within a circle defined by the recesses 20.

The members 21, in addition to their important functions as slackadjusters, vibration dampers, and noise reducers, also function toprevent jamming of the balls 14 between the gear 13 and the worm 12 atthe point of tangency thereof, FIG. 2. The resilient member 21 isadapted to be compacted Within its seating recess 22 when compressed bya pair of balls 14 at or near the point of tangency. As seen in FIG. 3,the radius of the recess 20 is large enough to receive the balls 14. Thewidth of the worm groove or inner ball race 23, defined by the lead ofthe helical worm tooth 24, is great enough to permit each ball 14 to bereceived therein in substantially frictionless contact therewith. Theballs 14 ride in their inner race 23 as defined by the continuoushelical tooth 24 and of the worm 12. The inner race 23 is a groove inthe worm 12 having a semicircular cross section.

Except for the presence of the slack adjusting member 21, jamming couldnormally be expected to occur at the point of tangency illustrated inFIG. 3 where the outer ball race, as defined by the cylindrical wall 25of the bore occupied by the worm 12 in the housing 15, is discontinued.Another important advantage of the presence of the slack adjusters 21 isthat the ball recesses 20 in the gear 13 need not be of the precisedimensions formerly required by other worm gear mechanisms for reliableoperation.

The outer ball race in addition to the outer cylindrical wall 25 of thehousing 15, is comprised of a tubular ball retainer 26 for providing arecirculating ball conduit, FIG. 3. This is necessary to provide meansby which the balls 14 can be returned to the opposite end of the worm 12after traveling the helical path along the length of the worm 12. Asseen in FIG. 3, if the worm 12 is turned in a clockwise direction aboutits turning axis, the balls 14 are fed through a cylindrical exitpassage 27 formed in the housing 15, into the retainer 26, and back intothe housing 15 into the inner race 23 of the worm 12 via a cylindricalreturn passage 28. However, if the worm 12 direction of travel'of theballs 14 is reversed. The passage, 28 becomes the exit passage,"and thepassage 27 becomes; the return passage. The retainer 26 is held in placeby shaft 11 therethrough. 'Screws 45 are" used to screw the plates 41,42 into place. The plates 41,42 serve as dust covers for the. bearingassemblies 16, 17, respectively.

Before the retainer 26 is attached to the leg 31 of the body membergroove,

a means enclosing said body member and extending lengthwise thereofretaining said antifriction elements a pair of laterally spaced U-shapedclips or brackets 30. 5] within said body member groove, The brackets 30are secured to, an upright rectangular leg 1 antifriction element returnmeans fixed to said encloslng or plate .31 of thehousing 15 by suitablefastening means, means and connected to theends of said body memsuch asscrews 32. The outer ends of the passages 27, 28 ber groove, V 3 arecounterbored to slidably receive the'terrninal ends of. a gear havinghelical recesses formed in the periphery the retainer 26. The ends ofthe retainer 26 are bent to thereof spaced ,apartja distance equal tothe lead of an angle 'of approximately thirty degrees from the ho'risaidbody member groove, and e v 7 zontal, FIGS. 1 and 3. Sharp corners andbends are "slack adjusting means carried bysaid gear in each of avoidedfor the smooth easy flow of the balls 14 during i said recesses adaptedto engage and urge said antithe circulation thereof. friction elementsagainst said body member at the The assembling of the mechanism 10 isrelatively simple point of power transmission between said body memandreadily accomplished. The worm 12 is inserted into her and said gear.the outer ball race25 of the housing 15. The double race III a devi ofthe charactel described; ball bearing assemblies 16, 17 are pressed overthe ends an elongated body member formed with an helical of the shaft 11extending beyond the worm 12 and into groove X d ng lengthwise thereof,corresponding ends of the cylindrical'outer race 25 formed. return meansCOIlHected t0 the endsof Said g antlin the bight of the J-shaped housing15. The gear 13 and f iction l m nts adapted to circulate Within saidits shaft 18 are inserted into the housing 15 with the-gear V groove andsaid return means, 13 occupying a cylindrical housing recess 33 and withthe i g m a s dispo ed about said body member and shaft 18 extendingthrough a drill hole 34 in a housing x e i g lengthwise thereof forretaining s d antlslide wall, FIG. 3. An L-shaped cover plate 35 forenfriction elements Within 'gr e closing the gear 13'is then securedtothe housing 15 by a g r having helical recesses formed in theperiphery suitable fastening means such as screws 36. The terminal 1thereof spaced apart a distance equalto the lead of end of the outputshaftlS is disposed in a drill hole 37 a groove in said b dymember, and7 formed in the cover plate 35. Both of the long upright slack adjustingmeans carried by said gear in a plural legs of the housing 15 and thecover plate 35 are each Of Said recesses adapted to g ge nd urge Saidcounterbored coaxially with the drill holes 34 and 37 for entifrictienelements against a y member a the insertion of a single row antifrictionball bearing asthe Point Of Power ission between'said body semblies 38,39, respectively. The output shaft 18 is member and Said g I journaledin the bearing assemblies 38, 39 on either side In a device as set f hin claim wherein said sla k of the gear 13. Cover plates 41 and 42 inFIG. 1 ar adjusting means comprise'flexible' tubular segments; disposedover the protruding ends of the input shaft 11 5- III a device of thecharacter described. and over the bearings 16 and 17, respectively, atopposite a Worm having an helical groove extending lengthwise ends ofthe worm 12. The plates41, 42 are alike and thereof, 7 y, i oppositelydisposed. The plates 41, 42 have central open} antifl'iction ballelements,- ings 43, 44 to accommodate the extension of the input housingmeans encircling Said Worm and eXtendiIlg lengthwise thereof forretaining said antifriction ball elements within said groove," ballreturn means connected to the ends of said groove, a gear havingrecesses formed in the periphery thereof housing 15 with the brackets 30and the screws 32, the 745 sp apart a distance equal to the lead of saidWorm groove 23 and-the retainer26 are fully loaded with Q and V a e theballs 14. Then the retainer 26 is fixed in'place on the V slackadjusting means carried by said gear in each of outside of the leg 31of'the housing 15 adjacent to the Said fecesses p to engage and vurgeSaid cover plate 35 I e V 7 friction elementsagainst said worm atthepoint of It will be understood that this invention can be modifiedpoweriransmissionbetween said r and Said gearto adapt it to variouscircumstances and conditions,*and i 6. In a device asfset forth in claim5, wherein said recesses of saidgear and said slack'a'dju-ster meanstherein are large enough to accommodate the contact two anti-'frictionball elements at the point of power transmission.

it is accordingly desired to comprehend within the purview of thisinvention such modifications as may be considered to fall Within thescope of the appended claims. 5

Whatis claimed p g 5 5' 7. An antifriction gearing' rnechanismcomprising, 1. An antifriction gearing mechanism comprising, a J'shapedhousing having a cylindrical the bight a worm'having' at leastonehelical groove formed in the thereof a e periphery thereof V e a wormhaving anhehcal groove formed m the peball retaining means connected tosaid. worm; said Egg? thereof dlsposed m housing cylmdrmalgilolcligleciriiihrzeltlegging means cooperat ng to de i e cylindricalinput shaft means coaxially connectedto the aplurality of balls in saidchannel, fi g h f a gear having-helical recesses formed in the peripherya 1:52: means 3 mg Sal S a t means m Sald thereof p ce 'df 'e dlstanceequel to d f 5 ball retaining means connected to said housing, said Wormgrooves Sald e l engaglng 33 g 111 e j housing having passagewaysconnecting said ball re- -sa1d recesses for transm tting rotative motionto said rai i means with said groove, ge from Said wormrafld. a apluralityofballs in said groove and said ball retain slack adjustingmeans carried in thebottom of: each or a ing means and saidconnectingspassa geways, i

said gear recesses for engaging said balls andurging '70 a gear'havinghelical recessesof arcuate cross section said balls into said wormgroove when said balls enter formed in the periphery' thereof spacedapart a dissaid recesses of said gear. a e a tance equal to the l ead orsaid groove, a 2. In a device of the character described, said ballsengaging said gear in the 'arcuate recesses an elongated body memberformed witlfman' helical r y thereof for having rotative motiontransmitted'there- 1 g g o ve ex ndinglengthwisethereof, V

tofrom said worm, I a 7 flexible slack adjusting means of arcuate crosssection carried in an arcuate recess formed in the bottom of each ofsaid gear recesses for engaging said balls and urging said balls intosaid worm groove when said balls enter said gear recesses and bearagainst said flexible slack adjusting means, output shaft means carriedby said gear and having one end journaled in one leg of said J-shapedhousing, an L-shaped housing cover having another end of said outputshaft means journalcd therein, said L-shaped housing cover beingconnected to said J-shaped housing,

said J-shaped housing and said L-shaped housing cover together havingthe general appearance of a rectangular solid, and dust cover meanscovering said antifriction means.

References Cited by the Examiner UNITED STATES PATENTS DON A. WAITE,Primary Examiner.

1. AN ANTIFRICTION GEARING MECHANISM COMPRISING, A WORM HAVING AT LEASTONE HELICAL GROOVE FORMED IN THE PERIPHERY THEREOF, BALL RETAINING MEANSCONNECTED TO SAID WORM, SAID GROOVE AND SAID RETAINING MEANS COOPERATINGTO DEFINE AN HELICAL BALL CHANNEL, A PLURALITY OF BALLS IN SAID CHANNEL,A GEAR HAVING HELICAL RECESSES FORMED IN THE PERIPHERY THEREOF SPACEDAPART A DISTANCE EQUAL TO THE LEAD OF SAID WORM GROOVE, SAID BALLSENGAGING SAID GEAR IN SAID RECESSES FOR TRANSMITTING ROTATIVE MOTION TOSAID GEAR FROM SAID WORM, AND SLACK ADJUSTING MEANS CARRIED IN THEBOTTOM OF EACH OF SAID GEAR RECESSES FOR ENGAGING SAID BALLS AND URGINGSAID BALLS INTO SAID WORM GROOVE WHEN SAID BALLS ENTER SAID RECESSED OFSAID GEAR.